PROJECT SUMMARY Adverse childhood experiences (ACEs) involving threat and deprivation early in development have pervasive and long-lasting negative effects on physical and mental health, including health risk behaviors, increased levels of biomarkers for disease, depression, posttraumatic stress disorder, and disruptive behavior disorders. The long-term harmful effects of early ACEs are mediated and moderated by biological, psychological, behavioral, and environmental processes later in development. Specifically, stress sensitivity models of risk have shown that the effects of early ACEs are exacerbated by exposure to stressful events and chronic adversity, including additional exposure to ACEs, later in development, with early adolescence representing a particularly vulnerable developmental period. Continued development of interventions to reduce physical and mental health problems associated with early ACEs and later exposure to stress depends on improved understanding of mechanisms of risk and resilience associated with exposure to stress during adolescence. Recent research suggests that important target mechanisms for interventions involves processes of emotion regulation (ER) and physiological reactivity (PR) in response to stress in adolescents and their caregivers, as deficits and disruptions in these processes increase the risk for physical and mental health problems associated with stress during adolescence (Compas et al., 2017). The proposed project will test a comprehensive multi-method protocol that includes a novel laboratory paradigm using video-mediated recall (VMR) and state-of-the-art measures to examine processes of emotion regulation in response to current stress, along with closely related processes of physiological reactivity, in adolescents who have been exposed to varying levels of ACEs early in development and their current caregivers. We will test the convergence of multiple measures of ER in adolescents and their caregivers, provide an initial test of latent indicators of adolescent and caregiver ER as predictors of symptoms of adolescent physical health problems and psychopathology, and set the stage for larger longitudinal and intervention studies with adolescents who have experienced early ACEs.